Embodiments of the present disclosure generally relate to implantable cardiac devices, and more particularly to implantable medical devices that communicate with an external device through radio frequency (RF) signals.
Numerous medical devices exist today, including but not limited to electrocardiographs (“ECGs”), electroencephalographs (“EEGs”), squid magnetometers, implantable pacemakers, implantable cardioverter-defibrillators (“ICDs”), neurostimulators, electrophysiology (“EP”) mapping and radio frequency (“RF”) ablation systems, and the like. Implantable medical devices (hereafter generally “implantable medical devices” or “IMDs”) are configured to be implanted within patient anatomy and commonly employ one or more leads with electrodes that either receive or deliver voltage, current or other electromagnetic pulses (generally “energy”) from or to an organ or tissue (collectively hereafter “tissue”) for diagnostic or therapeutic purposes.
Various IMDs are programmed and monitored by an external programmer or external home-based patient care system. For example, a patient may have an IMD that communicates with a base station within the patient's home or a programmer that is used by physicians to change settings within the IMD and/or retrieve data from the IMD. The base station or external programmer device receives data from the IMD about the patient's physiological state. For example, the IMD may transmit stored data or sensed physiological parameters to the base station. Based on the received data, the base station or external programmer device may adjust operating parameters for the IMD.
Conventional external programmers and base stations employ inductive communication techniques that facilitate communication between the IMD and a telemetry wand that is operatively connected to the base station. Typically, the wand of the base station or programmer is placed in close proximity to the IMD in order to establish a communication link. More recently, however, IMD telemetry assemblies have been proposed that employ far-field RF data communication techniques that do not require close proximity between the IMD and the wand of the programmer or base station. Further, some systems do not even include a separate and distinct telemetry wand, and the RF circuitry and antenna are embedded within the housing of the external programmer device or home base station.
Many telemetry systems communicate with IMDs using the Medical Implant Communication Service (MICS) band. Generally, the MICS band is an allocated frequency between 402-405 MHz. The MICS band enables a short-range, wireless link to be maintained between low-power implanted IMDs and an external programmer or base station.
In typical inductive telemetry systems that employ a wand, the IMD itself generally does not include a separate and distinct microprocessor that handles communication with the external device. Instead, in order to establish communication with the device, the wand is positioned in close proximity to the IMD, such as over a chest of an individual.
In contrast, typical RF-based IMDs include a microprocessor that is configured to handle communication with an external device, as well as control patient therapy. A typical RF-based IMD does not include hardware that handles a communication protocol. Instead, the microprocessor runs and operates to conduct RF communication with the external device. As an example, the microprocessor may run communication firmware in order to communicate with the external device.
IMDs may also operate based on tiered therapy. Each IMD may include a standard therapy mode in which the IMD operates to provide therapy to the patient. However, each IMD may also include a backup or restricted mode. The backup or restricted mode is activated if a malfunction or failure is detected within the IMD. The backup or restricted mode ensures that the IMD still provides basic therapy to the individual until the malfunction or failure is corrected, such as through a firmware update or patch that is communicated to the IMD through inductive telemetry, for example. That is, in order to update firmware or software on an IMD, even an RF-based IMD, a telemetry wand is typically used to communicate with the IMD and upload the firmware or software to the IMD.
In an RF-based system, during the backup or restricted mode, the microprocessor that typically is used to communicate with the external device is deactivated and reset. In short, the microprocessor may not run at all during the backup or restricted mode. Accordingly, RF communication with the external device is typically not possible, and there is no communication between the IMD and the external device. As noted above, in order to communicate with the external device, inductive telemetry, such as through use of a wand, is initiated.
Therefore, typical RF-based IMDs generally include inductive telemetry communication interfaces, such as telemetry coils, in order to communicate with the external device during a backup or restricted mode. Further, typical RF-based IMDs are able to download firmware and software upgrades through separate and distinct telemetry communication interfaces. As such, the cost and time of manufacturing a typical RF-based IMD is increased because of the separate and distinct inductive telemetry communication interfaces.